In synthetic organic chemistry, base catalysts may be divided into classes of base strength. Depending on the base strength, different catalyzed reactions are possible with each class of base. Metal carbonates and hydroxides, such as sodium and potassium hydroxide, are efficient catalysts for transesterification and have been used to produce sucrose polyesters and alkyl esters. Strong base catalysts, such as metal alkoxides (e.g. sodium methoxide, potassium t-butoxide (t-BuOK)) are broadly used in commercial organic syntheses and often preferred in specific reactions. The strong bases are often capable of catalyzing reactions at lower temperatures and in less expensive solvent systems. While some of these bases are prone to oxidation all are prone to inactivation by reaction with water.
It is known that the applications for the use of strong bases include, but are not limited to alkylations, arylations, acylations, aminations, condensations, eliminations, isomerizations, rearrangements, and Wittig reactions. Many examples may be found in standard laboratory textbooks (March's Advanced Organic Chemistry Reactions, Mechanisms, and Structure. 2000. 5th Edition. Michael. Smith, Jerry March). Numerous examples of the utility of strong bases may be found in both chemical and patent literature. For example, t-BuOK is employed in the synthesis of sidenafil (Viagra) (Dale et al. Org. Proc. Res. & Dev., 2000, 4, 17-22) and in the synthesis of the fungicide tebuconazole (WO/2000/044703); amination of nitroarenes (U.S. Pat. No. 5,262,539); condensation of ketones with succinic acid in a Stobbe condensation (Johnson and Schneider. Organic Syntheses, Colt. Vol. 4, p. 132 (1963); synthesis of substituted olefins via a Wittig reaction (Tago et al. Perkin 1, 2000, 2073-2078).
Reaney et al. (U.S. Pat. No. 6,822,104) utilize polyethylene glycol to conduct reactions with potassium hydroxide as a base and reported the synthesis of conjugated linoleic acid.
Reaney and Westcott (U.S. Pat. App. No. 20070049763) have developed strong base catalysts from polyether alcohols. However, based on the stoichiometry, they were not able to achieve more than 50% substitution of the free alcohol with the corresponding alkoxide, resulting in a relatively low concentration of titratable base.
U.S. Pat. No. 3,520,940 to Smith discloses a group I metal that may be used in the synthesis of polyalkoxide.
PCT Patent Application Publication No. WO 2008/115806 and Spanish patent application no. ES 2,277,727 disclose basic metal salts of glycerin for use as transesterification catalysts.